Enhanced optical and electrical characteristics of Si detectors integrated with periodic 1-D and 2-D semiconductor nanoscale structures

Nanostructuring the active region of metal-silicon-metal (MSM) photodetectors (PDs) with subwavelength periodic 1-D and 2-D nanoscale grating structures significantly modifies the optical absorption, reflectance and transmission properties of silicon. These modifications dramatically impact the electrical characteristics of the MSM PDs. The surface reflection is reduced from /spl sim/33% (planar Si) to /spl sim/4% (nanostructured Si) for triangular shaped nanostructures. The internal quantum efficiency of the MSM PDs increased from /spl sim/63% (planar) to /spl sim/80% (nanostructured) at /spl lambda/=700 nm. Also, a faster time constant (/spl sim/1700 ps for planar MSM PD to /spl sim/600 ps for nanostructured MSM PD) was achieved by enhancing the optical absorption near the surface where the carriers are efficiently and rapidly collected.